However, PCH files can range in size from about 250KB to several
megabytes or more, so you might not want to create many PCH files.
PCH processing might not always be appropriate, for example,
where you have an arbitrary set of files with non-uniform initial
sequences of preprocessing directives.
The benefits of PCH processing occur when several source files
can share the same PCH file. The more sharing, the less disk space
is consumed. Sharing minimizes the disadvantage of large PCH files,
without giving up the advantage of a significant decrease in compilation
Therefore, to take full advantage of header file precompilation,
you might have to re-order the
of your source files, or group
within a commonly used header file.
Different environments and different projects might have differing
requirements. Be aware, however, that making the best use of PCH
support might require some experimentation and probably some minor
changes to source code.